Allosaurus
Allosaurus is arguably one of the most well known Jurassic predators known. The name "Allosaurus" means "different lizard" alluding to its unique concave vertebrae (at the time of its discovery). Information The forelimbs of Allosaurus were short in comparison to the hindlimbs (only about 35% the length of the hindlimbs in adults) and had three fingers per hand, tipped with large, strongly curved and pointed claws. The arms were powerful, and the forearm was somewhat shorter than the upper arm (1:1.2 ulna/humerus ratio). The wrist had a version of the semilunate carpal also found in more derived theropods like maniraptorans. Of the three fingers, the innermost (or thumb) was the largest, and diverged from the others. The phalangeal formula is 2-3-4-0-0, meaning that the innermost finger (phalange) has two bones, the next has three, and the third finger has four. The legs were not as long or suited for speed as those of tyrannosaurids, and the claws of the toes were less developed and more hoof-like than those of earlier theropods. Each foot had three weight-bearing toes and an inner dewclaw, which Madsen suggested could have been used for grasping in juveniles.There was also what is interpreted as the splint-like remnant of a fifth (outermost) metatarsal, perhaps used as a lever between the Achilles tendon and foot. In 1991 "Big Al" (MOR 693), a 95% complete, partially articulated specimen of Allosaurus was discovered. It measured about 8 meters in length. MOR 693 was excavated near Shell, Wyoming, by a joint Museum of the Rockies and University of Wyoming Geological Museum team. This skeleton was discovered by a Swiss team, led by Kirby Siber. The completeness, preservation, and scientific importance of this skeleton gave "Big Al" its name; the individual itself was below the average size for Allosaurus fragilis, and was a subadult estimated at only 87% grown. The specimen was described by Breithaupt in 1996. Nineteen of its bones were broken or showed signs of infection, which may have contributed to "Big Al's" death. Pathologic bones included five ribs, five vertebrae, and four bones of the feet; several damaged bones showed osteomyelitis, a bone infection. A particular problem for the living animal was infection and trauma to the right foot that probably affected movement and may have also predisposed the other foot to injury because of a change in gait. Al had an infection on the first phalanx on the third toe that was afflicted by an involucrum. The infection was long lived, perhaps up to 6 months. It is known that Allosaurus led a dangerous life. The Allosaurus on display at the Smithsonian Institute has a smashed shoulder blade, many broken ribs, and a lower jaw so damaged that paleontologists didn't realize it was an Allosaurus jaw for over 100 years. But these were tough dinosaurs: Their bones show that they lived long enough for their wounds to heal. Allosaurus had extensions on its lacrimal bones which formed a brow horn over each eye. These horns varied somewhat in shape and size. Low ridges extended from them along nasal bones. Some theories on the purpose of the horns include display, weapons for combat, and possibly as effective sunshades. These horns, likely covered in keratin, are believed to have been fragile. Allosaurus probably spent time lurking in the undergrowth waiting for an unsuspecting herbivore to pass by. They may have also hunt in packs, preying on the stragglers in a large herd of herbivores, like the young, old, and wounded. Allosaurus may have used hunting strategies such as flesh grazing, pack hunting, and ambush attacks that utilized trachea crushing bites. It likely grasped its meal with its legs and mouth and pulled its meal apart. Its unusual gaping jaw has spurred debate regarding Allosaurus using its head like a hatchet to attack and slice at prey. In-Game Allosaurus will be in the early access of Prehistoric Kingdom. 3 species are depicted in the game as different skins, "A. maximus", A. europaeus, and A. fragilis. Gallery Prehistoric_Kingdom_Allosaurus_skins.jpg|Old skins ab6cc68a74220a5994dc707492947926.jpg|''Allosaurus'' ontogeny Allosaurus_01_Preview.png|Veiled/''A. europaeus'' Allosaurus_02_Preview.png|Marsh/''A. fragilis'' Allosaurus_03_Preview.png|Badlands/'A. maximus" Category:Dinosaurs Category:Theropod Category:Carnivore